Substrate coatings such as those applied to floor surfaces are known in the art. Such coatings are typically applied as a liquid that subsequently cures to form a durable layer over the underlying floor surface. Curing of the coating is often achieved through a thermal treatment and/or exposure to ambient conditions.
While effective, cure times for many conventional floor coatings may be substantial, e.g., anywhere from several hours to several days. To reduce lengthy cure times, floor coating materials formulated to cure relatively instantly when subjected to ultraviolet (UV) radiation have emerged. These coatings typically include photo-responsive components that cure when exposed to particular wavelengths of UV radiation. In addition to reducing cure time, UV curable coatings may also reduce material costs (e.g., by eliminating solvents) and/or operational costs (e.g., no conventional thermal curing equipment required).
Typically, UV floor coatings are cured by traversing the floor, after the coating material is applied, with a mobile UV illumination source. Exemplary apparatus and systems that may be used to effect curing of the coating material generally include a curing head that forms a shroud having an opening at the bottom, e.g., proximate the floor surface. UV bulb sources are located inside the curing head and are placed to direct UV energy downwardly through the shroud opening and to the coated floor surface. As the head passes over the coated floor surface, the coating material may cure relatively instantly.
While such systems and techniques are certainly effective, drawbacks remain. For instance, UV floor curing heads may often be positioned to provide a gap between the lower edges of the shroud and the floor surface. By making the gap too small (e.g., low shields), dispersion of stray UV light is minimized, but potentially undesirable contact between the shroud and undulations in the floor surface may occur. Conversely, by making the gap too large, excessive stray UV energy may pass outside of the shroud. Depending on the intensity of the escaping stray light and the composition of the floor coating material, the stray light may result in partial curing of the floor coating material that is laterally outside of the curing head (e.g., outboard of the curing head). In some instances, this partial cure may result in the formation of a visible line of surface differentiation in the floor coating that runs along one or both sides of the curing head. When the head is then passed directly over the floor coating containing this visible line, this line may become locked into the cured coating, potentially resulting in an aesthetically undesirable appearance.